The present invention relates to a field of art dealing with firearm safety devices. The fundamental function of a firearm safety device is to prevent accidental discharge of a weapon while it is loaded. Further, in an automatic weapon which operates in an "open bolt" or "rear seared" mode, it is necessary to prevent the safety device from being engaged unless the weapon is charged. The basis of this requirement is outlined below.
An open bolt firearm is that class of weapon in which firing is limited by holding the weapon's operating group near its rearmost position with a hook like projection called a sear, thus stopping the weapon with it's bolt open. The operating group is the reciprocating portion of a weapon's mechanism which accomplishes the mechanical actions necessary to produce automatic fire.
The basic shortcoming in prior art devices is related to an absence of a device that can prevent two undesirable possibilities in the use of an open bolt automatic firearm.
These possibilities occur if the safety, a device to prevent the sear from releasing the operating group and thus initiating firing, is engaged while the operating group is not at it's rearmost position. The weapon operator next attempts to manually pull the operating group to it's rear position in preparation for firing. This manual operation is required by the weapon's cycle of operation and is referred to as charging. As the sear is locked by the safety, it cannot move to allow the operating group to pass by and be hooked by the sear. At this point several things may happen.
Firstly, the operator may realize that the weapon is not completely charged and may apply excessive force in an attempt to complete charging. Excessive force may break mechanism parts and result in uncontrollable firing.
Secondly, the operator may not realize that charging is incomplete and may release the charging handle. Such action would permit a shot to be fired after which the automatic cycling of the operating group would break mechanism parts and again result in uncontrollable firing.
Accordingly, the present invention is intended as a solution to both undesirable and unsafe possibilities.